Modern technology allows musicians to reach large audiences through recordings and live sound amplification systems. Musicians often use microphones for live performance or recording. Microphones can offer good sound quality but may be prohibitively expensive and may be prone to acoustic feedback. Further, microphones are sensitive to variations in distance between the source and the microphone, which may limit the mobility of the performers on stage. Acoustic pickups give acoustic musicians an alternative to microphones. Pickups may consist of one or more transducers, attached directly to the instrument, which convert mechanical vibrations into electrical signals. These signals may be sent to an amplification system through wires or wirelessly. Acoustic pickups may be less prone to feedback, but may not faithfully re-create the sounds of the instrument. One type of acoustic pickups make use of piezoelectric materials to convert mechanical vibrations into electrical current. Often mounted under the instrument bridge of an acoustic instrument, piezoelectric pickups have been cited as sounding “thin”, “tinny”, “sharp”, and “metallic”. Other pickup designs have made use of electromagnetic induction and optical transduction techniques. Acoustic instruments with pickups installed, especially acoustic guitars, are sometimes referred to as “acoustic-electric”.
Sound reinforcement for acoustic instruments may be complicated by audio or acoustic feedback. Feedback occurs when sound from an amplification system is picked up by a microphone or instrument pickup and re-amplified. When feedback is especially severe, feedback loops can occur wherein a “howling” or “screeching” sound occurs as a sound is amplified over and over in a continuous loop. Acoustic instruments are, by design, well-tuned resonators, making instrument bodies and strings susceptible to such audio feedback. Acoustic instruments may be forced into sympathetic vibration by amplification systems, changing the instrument's behavior, and complicating live sound amplification solutions.
Like reference numbers and designations in the various drawings indicate like elements.